lib, vm: reimplement exit() as exception type

Instead of invoking exit(3) from uc_exit(), use a new EXCEPTION_EXIT
exception type to instruct the VM to shutdown cleanly.

This is required to not terminate the host program in case libucode
is embedded and loaded scripts invoke the exit() function.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/vm.c b/vm.c
index 15e510d..f4c56db 100644
--- a/vm.c
+++ b/vm.c
@@ -77,6 +77,7 @@ static const char *exception_type_strings[] = {
 	[EXCEPTION_TYPE] = "Type error",
 	[EXCEPTION_REFERENCE] = "Reference error",
 	[EXCEPTION_USER] = "Error",
+	[EXCEPTION_EXIT] = "Exit"
 };
 
 
@@ -2256,6 +2257,16 @@ uc_vm_execute_chunk(uc_vm *vm, uc_value_t **retvalp)
 
 		/* previous instruction raised exception */
 		if (vm->exception.type != EXCEPTION_NONE) {
+			/* VM termination was requested */
+			if (vm->exception.type == EXCEPTION_EXIT) {
+				uc_vm_reset_callframes(vm);
+
+				if (retvalp)
+					*retvalp = ucv_int64_new(vm->arg.s32);
+
+				return STATUS_EXIT;
+			}
+
 			/* walk up callframes until something handles the exception or the root is reached */
 			while (!uc_vm_handle_exception(vm)) {
 				/* no further callframe to pop, report unhandled exception and terminate */